1. Field of the Invention
The present invention relates generally to mechanisms used in agricultural planting machines for selecting and dispensing individual seeds and more particularly to such mechanisms which employ a vacuum pressure to singulate and dispense the seeds.
2. Description of the Related Art
It is well recognized that uniformity of seed spacing in the seed furrow is essential for achieving a field""s maximum crop yield potential and thus the profitability of the farmer""s operation. Modern agricultural planters use various types of seed metering devices which, ideally, are designed to select and dispense individual seeds at regular intervals. Unfortunately, however, most of these commercially available seed metering devices often fail to perform as ideally designed in that the seed meter will occasionally miss or skip a seed thereby resulting in gaps in the seed spacing, or, alternatively, the seed meter will dispense two or more seeds at a time (i.e., doubles or triples) instead of dispensing individual seeds.
The cause of most of skips or doubles can be attributed to factors such as lack of proper maintenance of the seed meter or the failure on the part of the farmer to change out components of the seed meter when switching between planting seeds of different shapes or sizes. Despite the knowledge that failure to perform proper maintenance or failure to change out components of the meter when switching to planting seeds of different sizes and shapes may result in lower yields, many farmers elect not to engage in these time-consuming practices during the rush of the planting season. Accordingly, there is a need in the agricultural industry for a seed metering device that requires little maintenance and one that can plant a wide range of different sizes and shapes of seeds and which is further capable of planting a wide range of seed populations without having to change out components, thereby minimizing down-time, while still maintaining desired uniformity and accuracy in selecting and dispensing individual seeds.
As identified above, there are various types of seed metering devices currently being used on modern conventional agricultural seed planters. These various types of seed meters are substantially divided into two categories on the basis of the seed selection mechanism employed, namely, mechanical or pneumatic. The commercially available mechanical meters include finger-pickup meters such as disclosed in U.S. Pat. No. 3,552,601, cavity-disk meters such as disclosed in U.S. Pat. No. 4,613,056, and belt meters such as disclosed in U.S. Pat. No. 5,992,338. Commercially available pneumatic meters include vacuum-type meters such as disclosed in U.S. Pat. No. 5,501,366, and compressed air meters. There are also commercially available meters that combine the seed selection mechanisms of both mechanical and pneumatic meters such as disclosed in U.S. Pat. No. 4,074,830. Of the various types of seed meters, vacuum-type meters offer certain advantages and desirable features over the other types of meters.
In general, most vacuum-type meters, such as those disclosed in U.S. Pat. Nos. 4,241,849; 4,285,444; 4,688,698; 4,793,511; 5,170,909; 5,392,707; 5,501,366; 5,542,364; 5,740,747; and 6,109,193, utilize a rotary disk or plate having one or more concentric circular rows of equally spaced apertures. A vacuum is applied to one side of the disk thereby creating a negative pressure differential on opposite sides of the disk. In use, the disk rotates through a seed reservoir located on the opposite side of the disk to which the vacuum is applied. The negative pressure differential causes seeds to be held or entrained over the apertures as the apertures rotate through the seed reservoir. Excess seeds are then removed by a seed stripper and the individual seeds that remain entrained over the apertures are then dispensed one at a time at a discharge point located on the path of travel of the apertures before the apertures re-enter the seed reservoir.
Another vacuum-type meter as disclosed in U.S. Pat. No. 6,142,086 discloses the utilization of a rotatable vacuum drum as opposed to a rotatable vacuum disk or plate as part of the seed selection mechanism. The vacuum drum of the ""086 patent includes a row of circumferentially spaced apertures about the outer circumferential periphery of the drum and further includes a seed tube for xe2x80x9cplucking the seedsxe2x80x9d off the rotatable drum. The use of a seed tube to xe2x80x9cpluckxe2x80x9d the seeds from the rotating drum may potentially damage the seeds which may effect the ability of the seed to germinate.
Those skilled in the art recognize that most of the commercially available vacuum-type meters typically require less maintenance than other types of meters since vacuum-type meters usually have fewer moving parts that tend to wear with use, particularly as compared to the finger-pickup type meters. Additionally, with vacuum-type meters, usually a single vacuum disk or drum can be used for planting a wider range of seed shapes and sizes without the need for changing out components and without sacrificing the performance of the seed meter. Finger-pickup meters, on the other hand, usually require the farmer to change out the backing plates or the seed stripper inserts when switching among seeds having a different sizes or shapes in order to maintain the same degree of performance. Similarly, with belt-type meters or seed cavity disk meters, it is likewise usually necessary to change the belts or the cavity disks, respectively, to accommodate different seed sizes and shapes.
Thus, while vacuum-type meters offer certain desired advantages over mechanical meters, most commercially available vacuum-disk meters suffer from certain other disadvantages relating to their manufacture. One particular problem relates to maintenance of the vacuum or pressure differential, particularly with respect to vacuum-type meters that utilize a vacuum disk as opposed to a vacuum drum. In vacuum-disk meters, the sealing arrangement between the disk and the housing must be sufficiently effective to minimize localized variations in the vacuum around the circumference of the disk. To minimize any irregularities between the seal of the disk and the housing, the disk is typically manufactured from a rather heavy stainless steel plate that must be precisely rolled and machined under very fine tolerances. Thus, vacuum-disks are typically expensive and difficult to manufacture. Accordingly, there is a need in the industry to provide a metering device which offers the features and advantages of a vacuum-type meter, but which is more easily manufactured and does not require the expensive machining operations and fine tolerances. Additionally, there is a need in the industry for a vacuum-type meter which will gently release the seeds such that the seeds are not damaged when discharged.
Furthermore, recent technological advances in global positioning systems (GPS) and availability of satellite imagery and yield monitors on harvesting equipment have enabled farmers to map their fields based on a number of conditions. Farmers are now able to match seed varieties to the various soil conditions that may be encountered in any given field. For example, a particular variety of seed may produce higher yields in sandy soil than in clay or loess soils which may be encountered based on the topography of the field. Additionally, certain varieties of seeds may have more disease resistance or will better tolerate field conditions where there may occasionally be standing water due to poor drainage. Therefore, there is a need in the industry for a planting system which allows the planter to switch between different varieties of seeds while on-the-go as the planter encounters different soil conditions in the field or where certain areas of the field require different disease resistance.
Finally, in most modern conventional agricultural planters, the seed meters (whether finger-pickup type, vacuum-disk type, cavity-disk type or belt-type) are typically mounted just below the seed hopper of the planter such that a constant supply of seeds from the seed hopper may gravity feed into the seed reservoir of the seed meter housing. Thus, the seed meters on most conventional modern planters are located eighteen to twenty-four inches above the ground surface and, as a result, require a seed tube to direct the seeds into the seed furrow after the singulated seeds are discharged from the seed meter. It should be appreciated, therefore, that as the planter traverses the field, some of the seeds may quickly free-fall through the eighteen to twenty-four inch long seed tube while other seeds may hit the sides of the tube and bounce within the tube before landing in the bottom of the furrow. The difference in time between those seeds which quickly fall through the tube versus those seeds that hit and bounce within the tube results in unwanted irregularities in the seed spacing.
Therefore, in some applications it may be desirable to eliminate the need for a seed tube altogether by mounting the seed metering device near the soil surface such that the singulated seeds are discharged from the seed metering device just a few inches above the bottom of the furrow. By mounting the seed meter near the bottom of the seed furrow, the seeds will be more accurately dispensed in the furrow and the irregularities in seed spacing caused by the seeds falling through the seed tube at different speeds will be significantly reduced if not completely eliminated. In this regard, it would be desirable to mount a seed meter such that it is disposed between the furrow opening assembly and the furrow closing wheel assembly of a conventional planter. Unfortunately, most commercially available vacuum-disk meters are too large in diameter or two wide to be disposed in the confined space between the furrow opening assembly and the closing wheels of a conventional planter.
Based on the foregoing, there is a need in the agricultural industry for a seed meter that provides accurate, consistent and uniform seed placement for various types of crops and can plant a wide range of seed populations without the need for changing out components. In addition, there is also a need in the industry for a seed metering and dispensing device that is readily adapted for retrofitting most conventional planters which will eliminate the need for seed tubes by being adapted for mounting between the furrow opening assembly and the furrow closing wheel assembly and near the soil surface such that the seeds are gently deposited directly in the seed furrow thereby improving seed placement accuracy.
A seed meter having a stationary housing defining a seed supply reservoir, a seed singulation area and a seed discharge area. The seed supply reservoir is in communication with a supply of seeds disposed within the seed hopper of the planter. The seed meter includes a rotatable drum disposed within the stationary housing. The rotatable drum has an interior vacuum chamber in communication with a vacuum source disposed on the planter. The rotatable drum further has an annular circumferential periphery with a plurality of equally spaced apertures therein and wherein at least a portion of the annular circumferential periphery rotates through the seed supply reservoir. The annular circumferential periphery of the drum is preferably V-shaped when viewed in cross section, but the circumferential periphery may also be beveled to one side or substantially horizontal in cross-section.
In operation, the suction force created by the vacuum source draws air through the apertures into the vacuum chamber thereby causing the seeds in the seed supply reservoir to be entrained over the apertures as the apertures rotate through the seed supply reservoir. A seed release is preferably disposed inside the rotatable drum in the seed discharge area. The seed release preferably has a portion biased against an inside surface of the annular circumferential periphery of the drum such that at least the portion of the seed release substantially covers at least one aperture at a time as the drum rotates such that the suction force through the apertures is substantially cut-off thereby gently releasing the seeds entrained over the apertures. In the preferred embodiment, a seed release disposed on the interior of the drum is used in combination with an exterior drum wiper secured to the housing in the seed discharge area of the meter to ensure that all seeds are removed from the apertures before the apertures re-enter the seed reservoir. In an alternative embodiment, the seed release may also utilize positive air pressure to discharge the entrained seed from the rotating drum. In yet a further embodiment, rather than using a seed release disposed on the interior of the drum, an exterior drum wiper, alone, may be used to remove the seeds from the apertures before the apertures re-enter the seed reservoir.
In a preferred embodiment, the seed meter is in communication with a seed hopper containing separate compartments for holding different varieties of seeds. In this preferred embodiment, the seed meter includes a diverter which can be manually or automatically triggered to switch between the different seed varieties while on-the-go.
The seed meter may be disposed below the seed hopper, as is conventional in most planters. However, the seed meter is preferably disposed near the soil surface, rearwardly adjacent the furrow opening assembly and forward of the furrow closing assembly of a conventional planter such that the seeds are discharged directly into the seed furrow thereby eliminating the need for a seed tube which effects the uniformity of seed placement in the furrow.
To the accomplishment of the above objects, features and advantages, this invention may be embodied in the forms illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and the changes may be made in the specific form illustrated and described within the scope of the appended claims.